Internal combustion engines may utilize direct fuel injection, wherein a precisely controlled amount of fuel is injected under high pressure into each engine cylinder, thereby increasing fuel efficiency and power output of the engine. In traditional direct fuel injectors, the injector nozzle hole configuration and geometry can regulate combustion characteristics and affect vehicle emissions. The fuel is typically injected from a sac at the tip of the fuel injector needle into the engine cylinder through a plurality of holes, configured in various forms to increase atomization and improve air-fuel mixing.
One example approach for improving air-fuel mixing with a direct injector is shown by WO 2004053326. Therein, a fuel injector nozzle comprises a plurality of nozzle holes and a freely moving ball located inside a swirl fuel passage in the fuel nozzle. The swirl generated by an injector needle, which swirls the free-moving ball to block holes in the fuel injector nozzle, controls fuel injection through the holes of the fuel injector nozzle.
However, the inventors herein have recognized some issues with the above approach. For example, the position of the free moving ball in the swirl fuel passage may not be precisely controlled to close or open specific nozzle holes, resulting in a randomized pattern of fuel spray through the nozzle holes that may result in fuel spray interaction. In addition, the random positioning of the free moving ball to block fuel spray through the nozzle holes may result in use of some nozzle holes more than other nozzle holes, which may result in longer fuel penetration and degraded emissions.
In one example, the issues described above may be addressed by a fuel injector system including an injector body with a plurality of nozzle holes and an injector needle coupled to an injector pin. The injector pin includes a curved fuel channel in fluidic communication with a fuel reservoir inside the injector pin. The injector needle and pin are housed inside the injector body, and the curved fuel channel is configured to be in fluidic communication with the plurality of nozzle holes when the injector needle is actuated.
As one example, an actuator coupled to the needle may be activated to push the needle downward, thus moving the pin down through a plurality of positions. At each position, one or more specific fuel injector nozzle holes are fluidically coupled to the fuel reservoir via the curved fuel channel, while all other nozzle holes are blocked. In this way, as the pin is moved downward, each set of nozzle holes injects fuel. The nozzle holes and curvature of the fuel channel may be arranged such that adjacent nozzle holes do not simultaneously inject fuel, thus avoiding interaction between the fuel spray from adjacent nozzle holes. In doing so, the number of nozzle holes may be increased and spray atomization may be enhanced while reducing spray penetration length, thus promoting fuel mixing and increasing combustion efficiency.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.